A Study on Extraction Methods and Primary Toxicity Level of Bio Colourants

Abstract

Bio-colourants for food are extracted from plant sources that it is becoming a huge demand in the global market of processed foods and confectionaries. Natural colours play a vital role in food safety and also in meeting the needs of food consumption practices for the growing crisis in the availability of healthy foods. Aim of the bio colours is to replace synthetic colours like sunset yellow FCF, Allura Red, Ponceau 4R, Amaranth and Brown HT as they are becoming a wide range of threat to the human race, especially in bringing psychological changes in children and adolescents. Usually bio-colourants are extracted from almost all the parts of a plant. But majority of the colours are extracted from leaves and barks, whereas few colours in specific are extracted from fruits, seeds and some from petals of flowers. In this study, bio-colouring agents such as madder roots (Rubia cordifolia), eucalyptus bark (Eucalyptus grandis), annatto seeds (Bixaorellana), roselle petals (Hibiscus sabdariffa) and tamarind seeds (Tamarindus indica) were identified and used in extraction of colours. The colours obtained were of different shades of red like: sangria red, rusty red and yellow red. These natural food colours were extracted from their natural sources through two processes:10 per cent aqueous extraction (reflux, boiling) and powdering the substances. The pH of the extracts was taken to know their level of hydrogen ion concentration. To verify,if these extracts are edible and stable, preliminary toxicology study was carried out in brine shrimp assay. On the other hand, every fourth day the discolouring of the extracts was constantly measured using Food Colour Reader. The aqueous extracts showed discolouring and formation of microbial layer even when preserved in refrigerator in sterilized glass bottles, whereas the powdered substances remained the same with no discolouring or microbial activity in it. The toxicity study has practically proved that the powdered substances in various concentrations of 100, 250, 500, 1000 and 1500 µg/ml has the overall lowest mortality rate in consideration to mean and standard deviation (M ± SD) of 11.7 ± 10.7, than to the aqueous extraction samples of 73.7 ± 22.8 respectively. This study is carried out to promote and incorporate bio-colours in foods that can be consumed on daily basis, replacing the commercially available hazardous food colourants.